PR0535342 - Laserfiche WebLink

Home Browse Search

LFR Inc. Site and it is likely that concentrations of pyrolytic oil constituents in groundwater will continue to reduce over time through natural attenuation processes, including dilution, dispersion, adsorption, and biodegradation. Based on the sampling results, it is apparent that pyrolytic oil has affected groundwater quality downgradient from the Site and that the extent of affected groundwater has not been thoroughly assessed in the downgradient direction. Additional groundwater monitoring may be necessary to further evaluate the groundwater quality, as discussed in Section 9.0. 8.0 RISK ASSESSMENT SUMMARY A "Human and Ecological Health Risk Assessment, Tracy Tire Fire Site, Former Royster Tire Disposal Facility Tracy, California," dated October 11, 2006 (LFR 2006c), was prepared by LFR using post-remediation soil and groundwater data. Direct contact with metals in soil was identified as the most significant complete exposure pathway for human receptors. Based on the HRA results, estimated health risks and hazards associated with metals in soil are below levels of regulatory concern. Therefore, direct contact to metals in soil at the Site is not anticipated to cause adverse health affects. Dissolved pyrolytic oil is present in groundwater downgradient from the Site. No formal process exists for performing human health risk assessment on petroleum hydrocarbons in groundwater. In addition, no health concerns are associated with the groundwater impacts at the Site because there is no identified complete exposure pathway to the affected groundwater. The source of the pyrolytic oil has been removed from the Site and it is likely that concentrations in groundwater will be reduced over time through natural attenuation processes including biodegradation. Based on the HRA results, soil excavation and removal activities appear to have sufficiently reduced on-site concentrations of chemicals of potential concern to levels below health concerns. 9.0 SUMMARY AND RECOMMENDATIONS During September 2003 through May 2006, approximately 387,435 tons of burned debris and affected soil were removed from the Site. Confirmation soil sampling and a Health Risk Assessment confirmed that the RAO established for the Site has been met. Soil containing concentrations of metals and pyrolytic oil above the cleanup goals was removed from the Site. Although groundwater sampling results conducted during 2003 through 2005 did not indicate that the tire fire affected groundwater quality within the property boundary, pyrolytic oil encountered in soil during excavation activities in the north-northwestern rpt-RA summ-Nov06-final-09025 Page 37